Low cover factor woven cellulose textile material resistant to corrugation in washing and tumble drying



United States PatentfO Low COVER FACTOR WOVEN CELLULOS'E TEX- TILE MATERIAL RESISTANT T CORRUGATION 1N WASHING AND TUMBLE DRYING Carlyle Harmon, Scotch Plains, N .L, assignor to Chicopee Manufacturing Corporation, a corporation of Massachusetts e No Drawing. Filed Jan; 29, lass, Ser. No. 711,805 11 Claims. c1. 8-116) This invention relates to a method for treating low cover factor cellulosic textile materials ,ofplain, twill or satin weave type to render them resistant to corrugation when washed and tumble-dried orcentrifugally dried, while substantially preserving their original softness, hand and absorbency. It also relates to such textile materials when treated according to the method of this invention.

The problem of corrugation Corrugation is the term used to describe the dis-, tortion out of the general plane of the material which takes place. in a low cover factor cellulosic textile material such as that of which baby diapers are madevafter the material has been laundered by washing, and either tumble-drying or centrifugal drying. Thecorrugated material displays alternate ridges and furrows arranged parallel to the direction of the filling yarns of the ma- 1 1 if no special precautionsare observed, rotational distorting forces present in the individual yarns, upon release,

produce distortion in said yarns out of thegeneral plane of the textile material. v

One type of low cover factor cellulosic textile material is gauze diaper fabric, which has been made commercial- 1y, by way of example, with thread count ranging from ,39 to 46 in the warp and from 35 to .40 in the weft, and

with yarn sizes ranging from 25s1to 35s inthe warp and from 22s to 45s in the weft, in both plain and birdseye weaves. The latter term refers to a fancytwill woven to give'a diamond eifect which is popular in'diaper cloth.. d

From this description of thread counts and yarn weights in low cover factor textile materials, it is seen that such materials are woven with a relatively open mesh., In these materials the individual yarns comprising the fabric are relatively free to act independently as contrasted with the yarns of more tightly woven fabrics,

such as 80 x 80 print cloth, in which the yarns are pressed closely together.

As will be explained'in more detail below, it is this independent-behavior of the individual yarns of a low cover factor textile material which produces corrugation of the fabric. 1

How corrugation is produced Ordinarily the warp yarns of a textile material are more highly twisted than the filling yarns. [For this reason, the warp yarns manifest greater rotational tendency when incorporated in the finished materials than do the 'Z,945,7 38 Patented July 19, ,1960

weaving process to greater longitudinal tension than are the filling yarns; thus the difierence between therotational tendencies of the warp and filling yarns which is due to the difference intheir original twists is further increased by the weaving process.v

Subjecting the cellulosic textile material to washing produces swelling of the fibers of the yarns, thereby increasing the angle of twist, which results in a further increase of the rotational tendencies to which the'yarns are subjected. If the wet fabric is dried in an automatic drier of the type in common use, in which drying is accomplished by.blowing ,of heated air through the articles to be dried while they are tumbled in a rotating drum, 'or if the articles are dried by extracting moisture in a centrifugal type drier,.the increased rotational tendencies in the yarns just referred to will producecorrugaltions in any low cover factor material of plain, twill, or satin weave type. a

Corrugations will usually not appear if the rotational tendencies of the wet yarns are dissipated or relaxed by passing the wet article through a wringer to remove most of the water before the final drying; by shaking the article out before placing it in the tumbler-type drier or centrifugal type drier; by hanging the article on an outdoor line to dry in. the wind; or the like, However, the drying of a large batch of articles such as diapers by transferring them in a group directly froman automatic washing machine into an automatic tumbler-type drier is so common as to make the avoidance of corrugations by other expedients than those just mentioned a highly important objective.- 7 h a V The rotational tendencies in the warp yarns of low cover factor textile materials of plain, twill, or satin weave type cause each individual warp yarn to assume a generally helical over-all form. To the extent that the warp yarns of the fabric have the same basic'twist and other physical characteristics, this general helical form will be substantially the same for each warp yarn, the high and low points being distributed at-about the same locations along the longitudinal axis of each such yarn. Thus, there will be a general correspondence between high points along all the parallel warp yarns.-'

Since the filling yarns are customarily of a lower twist than the warp yarns, they manifest a lesser rotational tendency than do the warp yarns. Consequently, the filling yarns do not become grossly undulated as do the warp yarns,- but on the contrary remain relatively straight in general form. 'Io'theextent that there tends to be any lack of correspondence between the highs and lows" of adjacent warp yarns, this is rectified by the relatively undistorted filling yarns, which actas guide rods, as it were, to bring the highs and lows of each separate warp yarn into correspondence along their respective-lengths. The greater filling yarns. ..They are likewise subjected during the relationship with the filling yarns.

flexibility imparted'to the warp yarns as a result of their wave form makethem susceptible to alignment of the highs and lows and still remainin compatible orthogonal 'The result of the correspondence between the highs and lows of adjacent warp yarns is the ridges and valleys that "comprisethe undesired corrugation's in the fabric. Corrugations-bccur in low 'but not in high cover factor textile materials because in a low cover factor material the warp -"yarns' ac t-'-rel at ively'independently of each other in the manner just'described', while in a'high cover factor material they are restrained from acting in this way. In terms of distorting forces and the resistances opposing such forces, it can be said that the average ratio of distorting force or free energy present in anyportion of yarn between immediately adjacent cross-overs (i.e., points at which the warp and filling yarns cross over each other) to the-resistances existing at the yarn crossovers is greater for low cover fabric than for high cover fabric. and thus corrugations occur in the former case but not the latter.

Advantages of this invention The special precautions referred to in the definition of low cover factor above which. will avoid corrugation of a low cover factor textile material may be mechanical in nature. Use of a proportion of? yarns of reverse twist, as. disclosed in US. Patent Re. 24,139, is an example of a method. for avoiding corrugations which is related to the structure, or mechanical make-up, of the fabric. This method, however, requires changes in the spinning and weaving methods and equipment. The present invention provides a chemical method of combatting corrugation by a simple padding and curing operation. This method follows the conventional weaving operation, which is in all respects unchanged.

The method of this invention is very effective in rendering the textile material resistant to corrugation. In addition, the original softness, hand and absorbency of the untreated textile material are substantially unaffected, and no undesirable deterioration of these fabric characteristics is produced. Likewise, although the fabric is treated chemically, it does not exhibit. any unacceptable toxic effect even measured by the strict standards applicable when the fabric is to be employed as a material for baby diapers. The beneficial effects of treatment of baby diapers, for example, with the method of this invention will continue through 50 or more launderings.

This combination of results from use of the present invention makes the invention of particular importance in the field of cloth diapers. However, it is also useful in other applications such as laparatomy packs and washable surgical face masks, where similarproblems are encountered.

Summary of the invention The method of this inventionis based on the discovery that if certain of the acetal condensation products. disclosed in US. Patent No. 2,785,947, are dissolved in an aqueous bathat a solution strength adapted to produce a certain increase in dry weight of the fabric to be treated, and a low cover factor textile material of a plain, twill, or stain weave type is impregnated with the bath and then cured at an elevated temperature, the textile material will be rendered resistant to corrugation, while having its original softness, hand and absorbency substantially unchanged.

M The acetal condensation products useful in, this invention are formed from certain aldehydes and any of a large number of alcohols.

The percentage of increase in the weight ofthetreated fabric is kept within certain ranges so as to provide sufficient interaction with the acetal condensation product to make the textile material resistant to corrugation, without at the same time introducing undesirable deposition of the condensation product that will adversely affect the softness and absorbency of the fabric.

- Aldehydes usable with this-invention Suitable aldehydes which may beconvcrted to acetals 1n the method of this, invention are formaldehyde, acetalidehyde, propanal, butanal,glyoxal, and mixtures thereof.

Aldehydes having more carbon atoms than those in the listjust given are unsuitable for use in the method of this invention, I a If desired, various materials such as, paraformaldehyde. ormalin, trioxane, methylal, and similar formaldehyd gl16fatll1g compounds maybe used as sources o formaldehyde.

Alcohols: usable with this invention" Suitable alcohols which may be reactedwith the abovementioned aldehydes to form acetals useful in this invention are methanol, ethanol, propanol j isopropanol,

'butanol, methoxyethanol, ethoxyethanol, methoxyethoxyethanol, ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, dipropylene glycol, dibutylene glycols and higher dialkylene glycols, polyalkylene glycols, polyhydric alcohols such as glycerine, mannitol and sorbitol, and glycol monoethers and partial ethers of polyhydriealcohols. In general, in the aforesaid alcohols, the monohydric alcohols contain from 1 to 5 carbon atoms; the alkylene glycols contain an alkylene radical having from 2 to 4 carbon atoms in a straight chain; and the polyhydric alcohols contain-from 3 to 6 hydroxyl groups and from 3 to 6 carbon atoms in the molecule. The term alkylene as used herein is understood to include a doubly unsatisfied aliphatic. radical containing a substituted or unsubstituted straight chain as aforesaid, having its unsatisfied valences on either adjacent or separated carbon atoms.

Suitable monomeric acetals useful in this invention are di-(hydroxyethoxyethyl) formal, di-(methoxyethoxyethyl) formal, di-(methoxyethyl) formal, di-(hydroxyethyl) formal, glyoxal tetramethyl acetal, glyoxal tetraethyl acetal, glyoxal tetrabutyl acetal, and mixed acetals such as methyl methoxyethyl formal, glyoxal dibutyl dimethoxyethyl acetal, dimethoxymethoxyethyl ether, or methyl hydroxyethoxyethyl formal or mixtures thereof.

The polymeric acetals which are useful in this invention are reaction products between an aldehyde and an al'kylene or polyalkylene glycol. Typical polymeric acetals may be prepared from diethylene glycol and formaldehyde; ethylene glycol and formaldehyde; diethylene glycol, formaldehyde and glyoxal; diethylene glycol, sorbital and formaldehyde; diethylene glycol and acetaldehyde; and the like.

In general, those polymeric acetals which have proved useful in this invention may be made starting with ethylene glycol, a propylene glycol, a butylene glycol, dipropylene glycol, dibutylene glycols, and higher dialkylene glycols, polyalkylene glycols, mixtures thereof, or their mixtures with diethylene glycol which are reactive with formaldehyde or other aldehydes to form water soluble prodducts or products which are dispersible in water, either alone or with the aid of appropriate adjuvants. Polyalkylene glycols, such as diethylene glycol, triethylene glycol, tetraethylene glycol, tripropylene'glycol and the like may also be used, either alone or in admixture with the aforementioned glycols. Likewise, polyols, such as glycerine, pentaerythritol and sorbitol, may be added to the alkylene glycols in amounts up to about 50 mole percent of the glycols for reaction with the aldehyde for forming water soluble or water dispersible products.

The alcohols used in this invention, when reacted with the aldehyde selected, must produce an acetal condensation product that is non-volatile at the curing temperature of at least 250 F. In other words, the componentsof the acetal must be such as to produce a product having a boiling point of above about C. (257 F.)

Preferred acetal condensation products Of the acetal condensation products which have been indicated as useful in the method of this invention, the

preferred compounds are the polymeric acetals derived from one of the specified aldehydes and atleast one dialkylene glycol in which the alkylene radical has 2 to 4 carbon atoms ina straight chain. Each molecule of these acetals contains at least two dioxyalkyle'ne radicals derived from the glycol and at least two alkylidene radicals derived from the aldehyde.

The most satisfactory acetal condensation products have been found to be those formed from diethylene glycol and formaldehyde, the molecular weight of the polyfortnal so produced being approximately 500.

Production of acetal The acetal condensation products used in the method of this invention are prepared by heating the aldehyde and alcohol in the presence of a small amount of a strong acidic catalyst. The catalyst may be selected fromsuh furic acid, alkane sulfonicacids, phosphoric acicls, and acid halides, such as zinc chloride, stannic chloride, aluminum chloride, acid clays, and the like. In general, those catalysts well-known to the art for alkylation, esterification and Friedel-Crafts condensation reactions may be employed in making the condensation products. "-Anaze'otropic liquid, such as toluene, benzene, xylene, e't'hylbenzene, and the like may be employed to facilitate removal of water and thus aid the condensation;

The condensation product thus obtained is a somewhat viscous liquid, completely soluble in water and in many organic solvents, such as toluene, benzene, xylene, etc. It is'also completely miscible in water. It is completely stable 'under neutral or basic conditions, as are its aqueous solutions. The odor associated with the compound is faint and ethereal.

Padding step The acetal condensation product prepared as described is applied to the cellulosic textile material by use of an aqueous'padding bath. The textile material is then passed through mangling rolls in order to control the percent dr ck p 1 r The acetal condensation product should be present in the padding bath in a quantity which will prodnce'the desired amount of reaction between the cellulosic textile material and the acetal during curing. If the amount of acetal reacted with the cellulosic fibers is too small, the textile material is not rendered as resistant to corrugation as is desired. However, if the increase in weight of the textile material is too great, the softness and absorbency of the fabric tendto be decreased, and in addition there'may be some undesirable tensile'strengthloss.

: "An increase in weight of the textile material treated by' the method of this invention from about 3% toabout 15% of the dry weight of the textile material produces adequate results. An increase in weight of about 7% to about has been found preferable. J An increase of about 9% gives the most satisfactory combination 'of characteristics in the treated textile material.

j v The percentage byweight of the padding bath which "is represented by'the acetal condensation product may be controlled, in. ways well-known in the art, in order to produce the desired percentage increase in the dry weight ofthe treated cellulosic textile material.

Curing step 7 Iii addition to the acetal, the padding bath must contain an. acidic-type catalyst which will be operative during the curing step. Magnesium chloride is preferred because of its low tendency to tender the cellulosic material, Other acidic catalysts such as zinc chloride, maleic anhydride, oxalic acid, ammonium chloride, ammonium thiocyanate, citric acid, tartaric acid, phosphoric acid, ethyl acid phosphate, ammonium sulfate, sodium bisulfate, etc., may be used.

7 The catalyst should be present. in an amount of about 5% to about 200% by weight of the acetal content in the bath. 7

Theimpregnated textile material is cured at a temperature of at least about 250 F. for about $6 to 10 minutes. The time of the cure varies inversely with the temperature. 1

After curing, the fabric may be washed lightly with a detergent and a mild alkali, rinsed thoroughly and dried. The inventionwill befurther explained by reference to the examples setforth below:

f EXAMPLE I A ltypicalipolyformal for use in treating low cover 'fa ctoi .textile. material in accordance with this invention 1 was; m he a awi s mm s Diethylene glycol l 106 Paraformaldehyde (91%) 33 Sulfuric acid.(9'9%) 0.1 Toluene 20 The parts given in this and the otherexamples below are all by weight. a

The compounds listed above are heated under reflux with a moisture trap inserted between the flask and the reflux condenser. After 1-8 parts of water of reaction are withdrawn from the reaction mixture, it is heated in vacuo with agitation to remove toluene. It is especially important to remove the toluene if the low cover factor textile materialto be treated with the acetal condensation product is to be used for the manufacture of diapers. Underconditions of 2,0 mm. of Hg and at temperatures up to 150 C. no volatile organic condensation product is obtained. The resulting product is then neutralized with dilute NaOH solution to a pH of 7'.

The product is completely soluble in water and in toluene. It has a faint ethereal odor and'is somewhat viscous. It is free of formaldehyde odor under normal room conditions. The product has a molecular weight of 480 (Rest) and a,.hydroxyl equivalent of '220, which indicates it has a linear polymeric structure. It has a specific gravity of 1.155 at 94 F.- The refractive index is N l.4'62. The molecular weight and hydroxyl equivalent of the condensation product of this example indicate that it possesses a polymeric structure, containing an average of four diethylene glycol units, as shown in the following formula: i

radicals derived from the diethyleneglycol and at least two'alkylidene radicals derived; from the formaldehyde. 1

The resulting acetal condensation product is employed for the treatment of a cotton diaper fabric--a'typical low cover factor textile material-Tin accordance with this invention. The diaper fabric consists of two layers of 100% cotton gauze woven together at'the selvages. In the warp there are 40 ends per inch of 25s yarn. In the filling there are 38 ends per inch of a 35s yarn;

An aqueous solution ismadeup containing 10%: by weight of the diethylene glycolpolyformal prepared .as described above. The solution also contains, 10% by weight of magnesium chloride to serve as a catalyst duringfthe subsequent curing operation. The solution is padded on the diaper fabric by passing the fabric through a padding bath and then betweed'manglerolls, where the liquid pickup is reduced to'l00% based on'the weight of thedryfabrim.

The fabric is'then placed on "afj clip tenter frame 'so as to hold it to the dimensions it p'flossessed'before impr'e'g nation and exposed to heat for a period of'60 seconds, which leaves the tenter frame at 270 F., to. drythe-fab; ric. The fabric is then cured for two minutes in a euringovenat 350 F, Theresulting fabric is washed to remove the catalyst and any unreacted polyformal, and

shows no corrugations whatsoever,

7 [Measurement of the absorbency of thetreated fabric shows that the resistance to'corrugation has been achieved with maintenance of the water absorption power of the fabric at about 95% or-even more of the original absorbency of the fabric; Inaddition, the softness and hand possessed by the fabric before-treatment are substantially unchanged. EXAMPLE 2 In .this example, another typical low cover factor textile material istreated "and tested by the same procedure and with the same acetal condensation product as in Example 1. The material treated is 100% cotton fabric which has a. thread count of 44 x 36 and of which 8.60 square yards weigh one pound.

The treated fabric is again compared with untreated fabric of the same weight and structure. The untreated fabriccorrugates badly after one washing in a tumblertype washer and drying in a tumbler-type drier. Under similar conditions, the treated fabric displays no corrugations whatsoever.

The treated fabric also retains substantially its original softness, hand and absorbency.

EXAMPLE 3 Another acetal condensation product for use in treating low cover factor textile material in accordance with this invention is prepared from the following components:

Parts Diethylene glycol 85 Dipropylene glycol 27 Paraformaldehyde (91%) 33 Toluene 2O Sulfuric. acid (99%) 0.1

These compounds are reacted as in Example 1. The resulting product is a viscous liquid which forms a crystalline mass below C. The product is soluble in water or'toluene and has a faint ethereal odor.

' The acetal condensation product made as just described is used in the treatment and testing, by the same procedure as described in Example 1, of the same low cover factor textilematerial as described in that example.

- The same test results are obtained as are described in Example 1, with the treated diaper fabric showing no corrugations whatsoever after washing and drying.

EXAMPLE 4 Another acetal condensation product for use in treatinglow cover factor textile material 'in accordance with this invention is prepared from the following components:

Parts Diethylene glycol 80 Sorbitolcrystalline 32 Paraformaldehyde (91%) 30 Toluene 2 Sulfuric acid (99%) .1

EXAMPLE 5 Another acetal condensation product for use in treating low' cover factor textile material in accordance with this invention is prepared from the following components:

Diethylene-glycol v I 106 Paraformaldehyde (91%) a j 52 Glyoxal (30%) 39 Toluene '20 Sulfuric acid (99%) 0.1

These components are reacted as in Example 1. The product is a somewhat viscous yellow liquid with a faint ethereal odor. The product is soluble in water and. in toluene.

The acetal condensation product made as just described is used in the treatment and testing, by the same procedure as described in Example 1, of the same low cover factor textile material as. described in that example.

The same test results are obtained as are described in Example 1, with the treated diaper fabric showing no corrugations whatsoever after washing and drying.

EXAMPLE 6 Another acetal condensation product for use in treating low cover factor textile material in accordance with this invention is prepared from the following components:

I Parts Diethylene glycol 101 Beta methoxyethanol 4 Paraformaldehyde (91%) 30 Toluene 20 Sulfuric acid (99%) 0.1

The above materials are reacted as in Example 1 to yield a viscous liquid possessing a faint ethereal odor and soluble in water. Its polymeric nature is shown by Rast molecular weight determination which has a value of 637.

The acetal condensation product made as just described is used in the treatment and testing, by the same procedure as described in Example 1, of the same low cover factor textile material as described in that example.

The same test results are obtained as are described. in Example 1, with the treated diaper fabric showing no corrugations whatsoever after washing anddrying.

The above detailed description of this invention has been given for clearness of understanding only. No unnecessary limitations shall be understood therefrom, as modifications will be obvious to those skilled in the an.

I claim:

1; A diaper resistant to corrugation in washing and tumbleor centrifugal drying while substantially preserving its original softness, hand and absorbency, said diaper being the product resulting from the heating of a low cover factor woven'cellulose textile material with an acetal as hereinafter defined, until a reaction between the cellulose and the acetal is eifected and the dry 'wei'ght of the starting cellulose material is thereby-increased by an amount betweenabout 3% and about 15%, said acetal having a. boilingpoint above about C. and being the product of condensation of an aldehydeselected from the group consisting of formaldehyde, acetaldehy'de, propanal, butanal, glyoxal and mixtures thereof, and an aliphatic hydroxyl-bearing compound selected from the group consisting of aliphatic monohydric alcohols containing from 1 to 5 carbon atoms, monoalkylene and polyalkylene glycols in which the alkylene radical has from 2 to 4 carbon atoms in a straight'chain, and aliphatic polyhydric alcohols containing from 3 'to 6- hydroxyl groups and from 3 to 6 carbon atoms and mixtures of the aforesaid aliphatic hydroxyl-bearing compounds.

2; A cotton diaper resistant to corrugation in washing I and tumbleor centrifugal drying while substantially preserving its original softness, hand and absorbency, said diaper being the product resulting from the heating of a low cover factor woven cotton material with an acetal as hereinafter. defined, until a reaction between the cotton and the acetal is effected and the dryweight of the starting cotton material is thereby increased between about 3% and about 15%, said acetal having a boiling point above about 125? C. and being the product of-condensation' of an aldehyde selected from the group consisting offormaldehyde, acetaldehyde, propanal, butanal, glyoxal and mixtures thereof, and analiphatic hydroxylbearing compound selected from the groupconsisting of aliphatic monohydric alcohols containing from lto carbon atoms, monoalkylene andvpolyalkylene glycols in which the alkylene radical has from 2 to 4 carbon atoms in a straight chain, and aliphatic polyhydric' alcohols containingfrom 3 to 6 hydroxyl groups and from 3 to ,6 carbon atoms and mixtures of the aforesaid aliphatic hydroxyl-bearing compounds.

3. A low-cover factor woven cellulose textile material resistant to corrugation in washing and tumbleor centrifugal drying, while substantially preserving its original softness, hand and absorbency, said corrugation-resistant material being the product resulting from the heating of a low cover factor woven cellulose textile material with an acetal as hereinafter defined, until a reaction between the cellulose and the acetal is effected and the dry weight of the starting cellulose material is thereby increased by an amount between about 3% and about said acetal having a boiling point above about 125 C. and being the product of condensation of an aldehyde selected from the group consisting of formaldehyde, acetaldehyde, propanal, butanal, glyoxal and mixtures thereof, and an aliphatic hydroxyl-bearing compound selected from the group consisting of aliphatic monohydric alcohols containing from 1 to 5 carbon atoms, monoalkylene and polyalkylene glycols in which the alkylene radical has from 2 to 4 carbon atoms in a straight chain, and aliphatic polyhydric alcohols containing from 3 to 6 hydroxyl groups and from 3 to 6 carbon atoms and mixtures of the aforesaid aliphatic hydroxyl-bearing compounds. 7

4. A low cover factor woven cellulose textile material resistant to corrugation in washing and tumbleor centrifugal drying, while substantially preserving its original softness, hand and absorbency, said corrugation-resistant material being the product resulting from the heating of a low cover factor woven cellulose textile material of the class consisting of plain, twill, and satin woven materials with an acetal as hereinafter defined, until a reaction between the cellulose and the acetal is effected and the dry weight of the starting cellulose material is thereby increased] by an amount between about 3% and about 15%, said acetal having a boiling point above about 125 C. and being the product of condensation of an aldehyde selected from the group consisting of formaldehyde acetaldehyde, propanal, butanal, glyoxal and mixtures thereof, and an aliphatic hydroxyl-bearing compound selected from the group consisting of aliphatic monohydric alcohols containing from 1 to 5 carbon atoms, monoalkylene and polyalkylene glycols in which the alkylene radical has from 2 to 4 carbon atoms in a straight chain, and aliphatic polyhydric alcohols containing from 3 to 6 hydroxyl groups and from 3 to 6 carbon atoms and mixtures of the aforesaid aliphatic hydroxyl-bearing I compounds.

5. A low cover factor woven cellulose textile material resistant to corrugation in washing and tumbleor centrifugal drying, while substantially preserving its original softness, hand and absorbency, said corrugation-resistant material being the product resulting from "the heating of a low cover factor woven cellulose textile material with an acetal as hereinafter defined, until a reaction between the cellulose and the acetal is effected and the dry weight of the starting cellulose material is thereby increased by an amount between about 3% and about 15%, said acetal having a boiling, point above about 125 C. and being the product of condensation of an aldehyde selected from the group consisting of formaldehyde, acetaldehyde, propanal, butanal, glyoxal and mixtures thereof, and at least one dialkylene glycol in which the alkylene radical has 2 to 4 carbon atoms in a straight chain, containing per molecule at least two dioxyalkylene radicals derived 10 from said dialkylene glycol and at least two alkylidene radicals derived from said aldehyde. I

6. A low'cover. factor woven cellulose textile material resistant to corrugation in washingiand tuinbleor'centrifugal drying, while substantially preserving its original softness, hand and absorbency said'corrugation-resistant material being the productresulting from the heating of alow cover factorwoven cellulose textile material with an acetal as hereinafterdefined, until a reaction between the cellulose and the acetalis effected and thedry, weight of the starting; cellulose material is thereby increased by an amount between about 3% and about 15%,v said acetalhaving a boiling point above about 125-- 'Crand being the product of condensation of an aldehyde selected from=the group consisting of formaldehyde, acetaldehyde, propanal, butanal, glyoxal and mixtures thereof, and a dialkylene glycol selected from the group. consistingof diethylene glycol, dibutylene' glycol and mixtures there ,of, containing per molecule at least two dioxyalltylene radicals derived from said dialkylene glycol and: at' least two alkylidene radicals derived from said aldehyde.

7. A low cover factor woven cellulose textile material resistant to corrugation in washing and tumbleor centrifugal drying, while substantially preserving its original softness, hand and absorbency, said corrugation-resistant material being the product resulting from the heating of a low cover factor woven cellulose textile material with an acetal as hereinafter defined, until a reaction between the cellulose and the acetal is effected and the dry weight of the starting cellulose material is thereby increased by an amount between about 3% and about 15%, said acetal having a boiling point above about C. and being the product of condensation of formaldehyde and diethylene glycol, containing per molecule at least two dioxyalkylene radicals derived from said diethylene glycol and at least two alkylidene radicals derived from said formaldehyde.

8. A low cover factor woven cellulose textile material resistant to corrugation in washing and tumbleor centrifugal drying, while substantially preserving its origi-- nal softness, hand and absorbency, said corrugation-resistant material being the product resulting from the heating of a low cover factor woven cellulose textile material with an acetal as hereinafter defined, until a reaction between the cellulose and the acetal is effected and the dry weight of the starting cellulose material is thereby increased by an amount between about 3% and about 15%, said acetal having a boiling point above about 125 C. and a molecular weight of approximately 500 and being the product of condensation of formaldehyde and diethylene glycol, containing per molecule at least wto dioxyalkylene radicals derived from said diethylene glycol and at least two alkylidene radicals derived from said formaldehyde.

9. A low cover factor woven cellulose textile material resistant to corrugation in washing and tumbleor centrifugal drying, while substantially preserving its original softness, hand and absorbency, said corrugation-resistant material being the product resulting from the heating of a low cover factor woven cellulose textile material with an acetal as hereinafter defined, until a reaction between the cellulose and the acetal is effected and the dry weight of the starting cellulose material is thereby increased by an amount between about 3% and about 15%, said acetal having a boiling point above about 125 C. and being the product of condensation of an aldehyde selected from the group consisting of formaldehyde, acetaldehyde, propanal, 'butanal, glyoxal and mixtures thereof, and at least one dialkylene glycol in which the alkylene radical has 2 to 4 carbon atoms in a straight chain and a polyalkylene glycol in which the alkylene radical has 2 to 3 carbon atoms in a straight chain, containing per molecule at least two dioxyalkylene radicals derived from said dialkylene glycol and at least two alkylidene radicals derived from said aldehyde,

IDEA lwcover factor woven cellulose textile material resistant to corrugation inwashing and tumbleor centrifugal fdrying, while substantially preserving its original softness', hand and absorbency, said corrugation-re sistant. material being the 'product resulting from the heatingot alow: cover factor woven cellulose" textile mate rial;- with an acetal: as hereinafter defined, until a reac tionbetween thercellulo'se and .theacetal 'is effected and the dry weight of the starting cellulose material is thereby. increased by an amount-between about-3 and about 15%, said acetal having a boiling point above about 125 C:'and being the product of condensation of an aldehyde selected from the group consisting of formaldehyde, acetaldehyde, propanal, butanal, glyoxal and mixtures thereof, and at leastonedialkylene glycol in which the alkylene radical has 2 to 4 carbon atoms in a straight chain and an aliphatic polyhydric alcohol containing from 3: to 6 hydroxyl groups and: from. 3 to 6 carbon atoms, containing: per molecule at least two dioxyalkylene radicals derived from said dialkylene glycol and at least two alkylidene radicals derived 'from said aldehyde.

. 11. A lowcover factor woven cellulose textile material resistant to corrugation in washing and tumble- "or centrifugal drying,whilesubstantially preserving its original softness, hand and absorbency, said corrugation-re sistant r'naterial being the product resulting from the heating of a low cover factor woven cellulose textile material with an acetal as hereinafter defined, until a reaction between the cellulose and the acetal is effected and the dry weight of the starting cellulose material is thereby increased by an amount between about 3% and about 15%, said acetal being the condensation product of diethylene glycol, formaldehyde and glyoxal, containing per molecule at least two dioxyalkylene radicals derived from said diethylene glycol and at least two alkylidene radicals derived from said aldehydes and having a boiling point above about C.

References Cited in the file of this patent UNITED STATES PATENTS Kress Mar. 19, 1957 Kress Mar. 19, 1957 Kress Mar. 19,1957 

1. A DIAPER RESISTANT TO CORRUGATION IN WASHING AND TUMBLE- OR CENTRIFUGAL DRYING WHILE SUBSTANTIALLY PRESERVING ITS ORIGINAL SOFTNESS, HAND AND ABSORBENCY, SAID DIAPER BEING THE PRODUCT RESULTING FROM THE HEATING OF A LOW COVER FACTOR WOVEN CELLULOSE TEXTILE MATERIAL WITH AN ACETAL AS HEREINAFTER DEFINED, UNTIL A REACTION BETWEEN THE CELLULOSE AND THE ACETAL IS EFFECTED AND THE DRY WEIGHT OF THE STARTING CELLULOSE MATERIAL IS THEREBY INCREASED BY AN AMOUNT BETWEEN ABOUT 3% AND ABOUT 15%, SAID ACETAL HAVING A BOILING POINT ABOVE ABOUT 125*C. AND BEING THE PRODUCT OF CONDENSATION OF A ALDEHYDE SELECTED FROM THE GROUP CONSISTING OF FORMALDEHYDE, ACETALDEHYDE, PROPANAL, BUTANAL, GLYOXAL AND MIXTURES THEREOF, AND AN ALIPHATIC HYDROXYL-BEARING COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALIPHATIC MONOBYDRIC ALCOHOLS CONTAINING FROM 1 TO 5 CARBON ATOMS, MONOALKYLENE AND POLYALKYLENE GLYCOLS IN WHICH THE ALKYLENE RADICAL HAS FROM 2 TO 4 CARBON ATOMS IN A STRAIGHT CHAIN, AND ALIPHATIC POLYHYDRIC ALCOHOLS CONTAINING FROM 3 TO 6 HYDROXYL GROUPS AND FROM 3 TO 6 CARBON ATOMS AND MIXTURES OF THE AFORESAID ALIPHATIC HYDROXYL-BEARING COMPOUNDS. 